In spite of the existing iOS project in the list of the solution it is not so easy to convert your C#- code into a running apple- iOS – App. Apple itself make some restrictions and like to make your live difficult. First without a connected Apple- machine like a Mac or a Macbook there is no way. An additional machine is absolutely unavoidable. We have decided to by a Mac mini, which is the cheapest possibility and spent about 500€. A connection to your network is also necessary, but a WLAN- connection is sufficient.
You have to install the latest versions of Xcode and Visual Studio for MAC on that machine. Then activate a connection to this MAC from your VS with your cross platform project: Menu Tools –> iOS –> Pair to Mac. Look for the correct IP- number and connect both machines. If connection is successful, your Win10- Visual Studio offers after selection of the iOS project a huge list of iPhone- emulators. Select one and play. Then an emulator is downloaded and can be started on your Win10- machine. There is no action necessary (except sometimes the input of the keychain- password) on the Mac, it can work completely in the background.
If you want to play your app on your iPhone this is much more complicated and needs some more steps to do. In Android you simply connect your phone with a USB cable to your PC and after activating of the development options (German: Entwickleroptionen) in the list of emulators your phone should be offered. This is all what you need.
If you think the same steps are sufficient for your iPhone, forget it. Connect first your iPhone using a Usb- cable with the Mac. You have now ask Apple for an allowance to load your software App on your mobile phone!
This is desribed in an additional pdf file you can download here.
If you want to publish your App in Apple store, you need a professional account and the steps are described in the Bachelor thesis of Yang Linhui.